Magnetic materials can be controlled by an electrical bias voltage
16.06.2011
Researchers at Aalto University have developed a method to electrically manipulate small magnetic structures in a well-controlled manner, which in metaphorical words resembles the synchronous rotation of a series of compass needles by an electrical bias voltage.
In the experiments conducted by the Nanomagnetism and Spintronics Group, magnetic layers were strongly coupled to ferroelectric elements using thin film growth techniques.
Researchers at Aalto University have developed a method to electrically manipulate small magnetic structures in a well-controlled manner, which in metaphorical words resembles the synchronous rotation of a series of compass needles by an electrical bias voltage. In the experiments conducted by the Nanomagnetism and Spintronics Group, magnetic layers were strongly coupled to ferroelectric elements using thin film growth techniques.
The magnetic needle of a compass aligns itself along the earth’s magnetic field. However, if the same needle is placed in an electric field, it does not respond. Yet, the ability to control magnetic elements by an electrical bias voltage rather than a magnetic field would open up new opportunities for the design of multifunctional devices including smart memories, programmable sensors, and tunable microwave components.
– The idea behind these hybrid materials is that the electrical field does modify the properties of the ferroelectric component and that the magnetic layer is forced to follow these changes by efficient energy transfer across the interface, Sebastiaan van Dijken explains.
Pivotal to the experiments was the development of a unique polarization microscopy technique that allowed for simultaneous imaging of ferromagnetic and ferroelectric domain patterns. Using this technique, full imprinting of ferroelectric patterns into magnetic thin films was demonstrated. More importantly, the strong one-to-one correlation between ferroelectric and magnetic domains was found to persist when an applied bias voltage altered the ferroelectric pattern and this enabled the writing and erasure of magnetic domains by pure electrical means. An example of electric-field controlled magnetic domain formation is shown in the video link below.
The video demonstrating the writing of magnetic stripe domains by an electrical bias voltage (youtube.com)
The research findings have recently been published in Advanced Materials, a distinguished scientific journal, and are expected to further stimulate investigations on hybrid ferromagnetic-ferroelectric materials and electric-field controlled magnetism. The experiments were conducted by graduate student Tuomas Lahtinen under supervision of Prof. Sebastiaan van Dijken.
Read the publication (onlinelibrary.wiley.com)
Contact information:
Prof. Sebastiaan van Dijken
NanoSpin
Department of Applied Physics
Aalto University School of Science
tel: +358-9-470 28477
sebastiaan.van.dijken [at] aalto [dot] fi
Tuomas Lahtinen
NanoSpin
Department of Applied Physics
Aalto University School of Science
tel: +358-9-470 28707
tuomas.lahtinen [at] tkk [dot] fi
